1. Field of the Invention
The present invention generally relates to a power storage apparatus that can be charged, and can supply power to a load, a fixing apparatus serving as the load of the supplied power, and an image formation apparatus equipped with the fixing apparatus, such as a copying machine, a printer, a facsimile apparatus, and a multifunctional machine capable of any combination of copying, printing, and facsimile operations.
2. Description of the Related Art
Conventionally, a technology of providing an auxiliary power storage apparatus in addition to a main power supply has been known (for example, Patent Reference 1). The technology aims at improving operability of the image formation apparatus by shortening a time required for the temperature of the fixing apparatus to rise when starting operations, the image formation apparatus using electrophotography methods. The technology also aims at reducing the power consumption of the fixing apparatus for energy savings.
The fixing apparatus is usually constituted by a fixing roller that includes a heating member, and a pressurization roller that contacts the fixing roller with pressure.
In the image formation apparatus, a toner image is formed on the surface of a recording medium that is conveyed along a conveyance path of the image formation apparatus. The recording medium that supports and carries the toner image, which toner image is yet to be fixed, further travels along the conveyance path at a predetermined conveyance speed, and reaches the fixing apparatus. Then, the recording medium travels between the fixing roller and the pressurization roller (called a nip), the fixing roller applies heat to the recording medium, and both rollers apply pressure to the recording medium such that the toner image is fixed. The recording medium carrying the fixed image is sent out from the nip, and is discharged from the image formation apparatus.
The image formation apparatus includes a main power supply that is connected to commercial main power, and provides power to loads, such as the fixing apparatus, of the image formation apparatus. In addition to the main power supply, the image formation apparatus includes an auxiliary power supply consisting of a power storage apparatus that provides auxiliary power by discharging stored power to the fixing apparatus as required.
The power storage apparatus includes
one or more capacitor units (cell units) that are capable of charging and discharging,
a switching unit that switches between charging and discharging states of the capacitor units,
a converting unit that rectifies alternating current power (AC) provided from the commercial main power supply into direct current (DC) power, the DC power being provided to the capacitor units,
devices, such as a FET, and
connection terminals for providing power to the loads, all of which are electrically connected as required.
When the main power supply of the image formation apparatus is turned on (i.e., when the image formation apparatus is started), while the main power supply connected to the commercial main power supplies power to the fixing apparatus, the power storage apparatus serving as the auxiliary power supply also supplies power to the fixing apparatus. Accordingly, power that is greater than rated (e.g., 100V 15 A of the commercial main power) can be provided to the fixing apparatus, the power supplied by the power storage apparatus being added in. In this manner, the fixing roller can reach a desired temperature (fixing temperature) in a short time. Therefore, the image formation apparatus can become operational in a short time even after the main power has been disconnected for a long time, and the temperature of the fixing roller can be held low during a standby mode. In this way, the operability of the image formation apparatus is improved; and since the temperature of the fixing roller can be set up lower while in standby, the power consumption of the image formation apparatus is reduced.
Further, in addition to when the image formation apparatus is to start up initially, when there is great power consumption (for example, when image formation is continuously performed, when a document reading unit is operating, and when resuming operation after a prolonged standby state), the power storage apparatus provides the additional power to the fixing apparatus. In the cases such as exemplified above, the power storage apparatus supplements the insufficient power provided from the main power supply to the fixing apparatus. In this manner, stable and sufficient power is provided to the fixing roller of the fixing apparatus irrespective of the operation modes of the image formation apparatus, and the fixing temperature of the fixing roller can be properly maintained. Accordingly, even if the heat capacity of the fixing roller is small, the time required for the fixing roller to reach the operational temperature can be shortened while the fixing nature of an output image is always maintained at a proper level. In this manner, the fixing temperature while at standby can be lowered, the standby power consumption can be reduced, the heat dissipation loss is reduced, and as a result, energy savings are attained.
In addition, the capacitor unit of the power storage apparatus can be charged at any time as required after the image formation apparatus is started, when the image formation apparatus is operating at power less than the power available from the main power, and a part of the main power can be supplied to the power storage apparatus.
[Patent reference 1] JPA, 2001-66926